Hendrix I, Carels C, Kuijpers-Jagtman A M, Van 'T Hof M
Department of Orthodontics, School of Dentistry, Oral Pathology and Oral Surgery, Catholic University of Leuven, Belgium.
Am J Orthod Dentofacial Orthop. 1994 Apr;105(4):345-9. doi: 10.1016/S0889-5406(94)70128-8.
The purpose of this study was to determine the extent of apical root resorption, after fixed appliance therapy, in the posterior part of the dentition, and to evaluate if predisposing factors can be pointed out retrospectively. Tooth length in the posterior part of the dentition was measured on pretreatment and posttreatment orthopantomograms of 153 patients who were treated with standard edgewise appliances. Pretreatment and posttreatment tooth lengths were determined, and an attempt was made to explain the differences by sex, age, stage of root formation at onset of orthodontic treatment, extraction versus nonextraction therapy and treatment duration. Patients were divided into two groups according to their root formation. Group A consisted of patients with incompleted root formation at onset of orthodontic treatment except for the first molars. Group B consisted of patients where root formation was completed with the exception of second and third molars. Posttreatment tooth lengths of groups A and B were compared with pretreatment tooth lengths of group B with a paired t test, and correlations with the variables were calculated with multiple regression analysis only in group B. Posttreatment group A showed no significant differences with the mean root lengths of pretreatment group B. Differences between the mean pretreatment and posttreatment root lengths in group B were significant. Posterior teeth showed root shortening during active orthodontic treatment independent of sex, age, extraction versus nonextraction therapy, and duration of active treatment. Teeth with incompleted root formation at onset of orthodontic treatment showed root lengthening during active treatment, yet did not reach their "normal" tooth length.
本研究的目的是确定固定矫治器治疗后牙列后部根尖吸收的程度，并评估是否可以回顾性地指出诱发因素。在153例接受标准方丝弓矫治器治疗的患者的治疗前和治疗后的曲面断层片上测量牙列后部牙齿的长度。确定治疗前和治疗后的牙齿长度，并试图从性别、年龄、正畸治疗开始时的牙根形成阶段、拔牙与不拔牙治疗以及治疗持续时间等方面解释差异。根据牙根形成情况将患者分为两组。A组由正畸治疗开始时除第一磨牙外牙根未完全形成的患者组成。B组由除第二和第三磨牙外牙根已完全形成的患者组成。采用配对t检验比较A组和B组治疗后的牙齿长度与B组治疗前的牙齿长度，并仅在B组中用多元回归分析计算与各变量的相关性。治疗后A组与治疗前B组的平均牙根长度无显著差异。B组治疗前和治疗后平均牙根长度之间的差异具有统计学意义。后牙在积极正畸治疗期间出现牙根缩短，与性别、年龄、拔牙与不拔牙治疗以及积极治疗持续时间无关。正畸治疗开始时牙根未完全形成的牙齿在积极治疗期间牙根伸长，但未达到其“正常”牙齿长度。
